Catheters are used to remove unwanted tissue from the body. Atherectomy catheters are used to remove material from a blood vessel to open the blood vessel and improve blood flow through the vessel.
One problem that occurs when removing material from a blood vessel is that the material may be either soft or hard and may vary during the cutting process. As such, the cutting element should be able to cut both hard tissue and soft tissue. Another problem that occurs when using a rotating cutter is that particles of material tend to be displaced in a direction tangential to the cutter, away from the catheter and away from catheter based particle collection structures. It is therefore also desirable to direct cut particles towards the catheter, and especially towards a catheter based particle collection structure.